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Across 3. the removal and transport of material by wind, water or ice. 6. loose mixture of small mineral fragments and organic material 7. the grinding and wearing down of rock into new substances 10. process by which water flows into cracks in rock and expands as it freezes 13. the breakdown of rock into smaller pieces 14. the main reason farmers use crop rotation is to slow down the process of 17. rock that is the source of soil 19. very small particles of decayed plant and animal material in soil 20. the acid that is normally involved in the formation of caves 21. breakdown of rock by physical means

Down 1. when farmers plow across the slope instead of up and down a hill 2. soft, less weather resistant rocks wear away 4. chemical reaction which an element combines with oxygen to form an oxide 5. a process farmers use to change a steep field into a series of smaller flat fields 8. chemical breakdown of rock into new substances 9. various methods by which humans take care of the soil 11. process that rainwater dissolves and carries away minerals and soil 12. precipitation that contains acid due to air pollution 15. the top layer of soil that generally contains humus 16. rust is produced by the oxidation of this mineral 18. layer of rock beneath the soil